In recent years, miniature motors (i.e., micro-motors) have been extensively used in a wide field including a variety of equipments, such as for example, air conditioners of automobiles, CD (compact disc) players, copying machines, compact cameras, compact electric equipments, mobile phones, toys or the like. At present, a variety of miniature motors are designed and developed for application in increasing various field, particularly in miniaturization in weight and size with more performance.
A kind of typical miniature motor includes a rotor and exciting coils wound around a part of the stator. The miniature motor is driven to rotate by charging an exiting current to the exciting coils. In the case where the exciting coils are used, a considerable number of windings are required for the exciting coils. If the diameter of the wires for the coils is reduced to as small as 10 micrometers or less for the purpose of miniaturization of the motors, the exciting coils tend to be easily broken. This causes the exciting coils to be extremely difficult to be wind around the stator.
Accordingly, the exciting coils should be inevitably thick and large, and it is very difficult to miniaturize such motors, as a whole. On the one hand, such thick and large dimensions are undesirable and unsatisfactory for a demand of compact and lightweight in various portable devices, such as mobile phones and digital cameras.
On the other hand, the thicker and larger of the exciting coils, the more heat is generated therefrom. Accordingly, when being operated for a long period, the exciting coils could be prone to overheating. This would produce undue interference and influence on the miniature motor and other related components in some aspects, e.g., performance properties and lifetimes. For example, in a camera using the miniature motor, frequent photographic operation may overheat the optical components, thereby decreasing the imaging properties (e.g., refractive index and functional structure) of the optical components.
What is needed, therefore, is a miniature motor that is compact and lightweight and that has a relatively long operating lifetime.